Nortel Networks NN43001-121 - Manual (Page 20)

20 Converged Office component overview
Media gateways translate the following protocols between the
circuit-switched PSTN network and the packet-switched Enterprise Voice
infrastructure:
• Signaling protocol—SS7 and other protocols on the PSTN translate
to SIP for Enterprise Voice
• Transport protocol—T-Carrier or E-Carrier on the PSTN convert to RTP
or Secure Real-Time Transport Protocol (SRTP) for Enterprise Voice
From the Nortel perspective, the CS 1000 functions as a media gateway for
the clients of the OCS 2007 server.
Mediation Server
The Mediation Server provides signaling and media translation between the
Enterprise Voice infrastructure and a CS 1000 gateway.
Figure 3
CS 1000 and OCS 2007 logical network elements
The Mediation Server provides the following functions:
• translates SIP over Transport Control Protocol (TCP) (on the CS 1000
gateway side) to SIP over mutual Transport Layer Security (TLS) on the
Office Communications Server side
• encrypts and decrypts SRTP on the Office Communications Server side
• translates media streams (G.711) on the CS 1000 gateway side and RT
Audio on the Office Communication Server side
Nortel Communication Server 1000
Nortel Converged Office Fundamentals — Microsoft Office Communications Server 2007
NN43001-121 01.03 Standard
Release 5.0 30 April 2008
Copyright © 2005–2008, Nortel Networks
.